Marine anti-fouling

ABSTRACT

A method of significantly reducing marine fouling is taught, incorporating the use of light in the area around an underwater surface, to detract zoo plankton and salps. These marine organisms are generally nocturnal to avoid optical predators such as fish. As a result they will avoid bright areas. 
     Lights can be provided in fenders around a boat or the like, which can direct light to the area around an underwater surface of the vessel. Alternatively lights could be positioned over the underwater surface. In addition, the underwater surface can be made reflective to increase the light levels around the vessel. In a further alternative, the underwater surface can be coated in a bio or chemo-luminescent coating.

The present invention relates to the reduction in fouling on the underside of a boat or other underwater surface.

When a boat or other object is left in water, the surface area thereof exposed to the water becomes home to a variety of marine life forms. These can cause damage to the surface, reducing the useful life period of the object, and in the case of a boat or the like can cause considerable drag when moving through the water.

Various means have been used to reduce the fouling that occurs. In particular paints including substances toxic to marine life forms have been used. However, now with the increase in awareness of the need for conservation such substance are falling out of favour. Other paints have been used designed to prevent adherence of marine life forms, however, these have generally been less that totally effective and thus it has been necessary to look for further alternatives.

In my earlier patent GB 2385026, I described a method of using light to attract fish and other marine predators to feed on marine organisms that cause fouling. For example lighting the hull of a boat or structure fixed in the water will attract fish and other predators to feed on organisms attached thereto. However, I have now found that light can also be used for a different purpose.

The object of the present invention is to provide an improved method of reducing marine fouling.

According to the invention there is provided a method of reducing fouling on an underwater surface comprising using light around the surface to suppress the presence of zoo-plankton and salps.

Zoo plankton and salps are generally nocturnal. They rise to the surface of the water at night and descend during the day. This is in order to evade fish and the like, who are optical predators. The light provided by the invention simulates daylight, which is thus avoided by the zoo plankton and salps. This is particularly useful during night or in dark areas.

Zoo plankton includes the larval forms of marine life that case fouling of underwater surfaces, in particular barnacles and mussels.

While the method may be applied to any underwater surface, it is particularly convenient for use around boats and the like.

In the preferred method, the light source can be provided in the fenders around the boat. These can be positioned to provide a good level of light around the hull of the boat.

Alternatively, LEDs can be provided over the underwater surface.

Additionally or alternatively the surface may be silvered or coated in metal flakes. These will reflect the light.

In a further alternative, the surface may be covered in a luminescent coating. The luminescence may be bioluminescence or chemo-luminescence.

According to a second aspect of the invention there is provided a fender for a boat or the like, the fender incorporating a light.

Preferably the light will be directed to illuminate the underwater section of the boat or the like.

The light may be produced from incandescent bulbs or from LEDs.

Conveniently the fender may also incorporate mirrors and/or reflectors to direct the light on to the under water section of the boat or the like.

To help understanding of the invention, a specific embodiment thereof will now be described by way of example and with reference to the accompanying drawings, in which:

FIG. 1 is a cross-section of a boat hull, the boat being provided with lights provided in the fenders.

FIG. 2 is a side view of the boat of FIG. 1;

FIG. 3 is a cross-section of a fender used on the boat of FIG. 1;

FIG. 4 is a cross section of another fender according to the present invention; and.

FIG. 5 Is a cross section of a third fender according to the invention.

Referring to FIG. 1, the boat 10 thereshown is provided with fenders 12 according to the present invention. Fenders 12 are usually provided on boats to prevent damage to the boat when mooring or coming along side another vessel or jetty. However, according to the invention the fender can also be used as a light source for suppressing zoo-plankton and salps that cause fouling on underwater surfaces.

The fender 12 includes a body 14, of a plastics material and designed to absorb the shock of impact with a landing or other vessel. In the body there is provided a light source 16 and power source 18. As shown the power source is a rechargeable battery, however in some boats having their own power supply, the power source for the light could be provided from the boats own power supply. Alternatively the power source could include a solar panel, wind power or shore power.

As shown the inside 20 of the fender 12 is provided with a reflective coating to maximise the light output from the light source.

The base 22 of the fender 12 is provided as a lens 24 to transmit the light on the underwater surface of the boat. The lens is mounted such that the light can be focused and directed to ensure as much as of the underwater surface area as possible is illuminated.

Surface areas that spend a regular and significant proportion of time under water, such as the under side of a boat, are used by marine life as an habitat. Life forms such as the larval form of barnacles and muscles are part of the zoo-plankton and at a particular stage in their life-cycle then require such a habitat on which to settle. This growth on underwater surfaces is known as marine fouling and on boats can cause considerable drag.

Zoo-plankton and salps are preyed upon by fish and the like and who hunt using their vision. In order to minimise predation, zoo-plankton and salps rise to the surface at night when there are low levels of light and sink during the day to the deeper darker water.

In order to avoid optical predators, zoo-plankton and salps avoid bright areas and will thus tend to stay away from a lit underwater surface. As a result, fouling by zoo-plankton and salps will be reduced.

In addition, with the passage of vessels around the world, there can be a consequential passage of marine life as “hitchhikers”. This is known as bio-contamination. In areas with delicate eco-systems, such as Australia, this can be extremely damaging. Thus the reduction of marine fouling on boats and the like will also significantly reduce the bio-contamination.

Now turning to FIG. 4, the fender thereshown is a belt fender 30. The fender is semi-submersible, hangs vertically in the water and is provided with a light source 32. The light source provides sufficient light to illuminate the hull of a boat 34 on which it is hung, thus significantly reducing marine fouling. Conveniently the fender is segmented, and thus can be used by boats of different sizes, large boats using more segments. The segments can be connected together mechanically and electrically thus enabling any number of segments to be used.

FIG. 5 is a another fender according to the invention. The fender 40 thereshown is a ring fender, and is again segmented. A light source 42 is provided in the fended which illuminates the hull of the boat and the surrounding area, thus significantly reducing marine fouling. As before the segments are connected electrically and mechanically, allowing any number of segments to be connected together, for use on any sized boat 44.

The invention is not intended to be restricted to the details of the above described embodiment. For instance, light sources may be provided separate from the fenders, on specially designed lighting stations. Alternatively, the underside of a boat or the like could be provided with lights incorporated into the hull. In a further alternative, the light could be provided in the form of chemo-luminescence or bio-luminescence. 

1. A method of reducing fouling on an underwater surface comprising using light around the surface to suppress the presence of zoo-plankton and salps.
 2. A method as claimed in claim 1, wherein the underwater surface is the hull of a boat or the like.
 3. A method as claimed in claim 1 or claim 2, wherein the light source is provided in fenders around the boat.
 4. A method as claimed in claim 1 or claim 2, wherein the light source is LEDs spaced over the underwater surface.
 5. A method as claimed in claim 3 or claim 4, wherein the underwater surface is silvered or coated in metal flakes to reflect light.
 6. A method as claimed in claim 1 or claim 2, wherein the underwater surface is covered in a luminescent coating.
 7. A method as claimed in claim 6, wherein the luminescence is bioluminescence
 8. A method as claimed in claim 6, wherein the luminescence is chemo-luminescence.
 9. A fender for a boat or the like, the fender incorporating a light.
 10. A fender as claimed in claim 9, wherein the light is directed to illuminate the area around the underwater section of a boat or the like.
 11. A fender as claimed in claim 9 or claim 10, wherein the light is produced from incandescent bulbs or from LEDs.
 12. A fender as claimed in claim 9, 10 or 11, wherein the fender also incorporates mirrors and/or reflectors to direct the light to the area around the under water section of the boat or the like.
 13. A method of reducing bio-contamination by sea-transport, comprising using light around the underwater surface of a vessel to suppress the presence of zoo-plankton and salps. 